Bake HVP on BOS

See page on Viewport Replacement, Bake Viewport on BOS
Take HVP off BOS and put on transit case
- Always check transit case viton seal
- If transit case isn't available, carefully use a blank

Discuss the Plan

Discuss the game plan with the HVP diagram at the cubicle. Removal and install is not trivial.
We decided to take the 2.75" to 4.5" nipple off of the SF to help hold HVP assembly parts as we disassembled and reassembled.
We could hold it 2.75" down, HVP end up, with clean foil wrapped around the 2.75" end.
To reassemble, we'd build the viewport back up on top of kimwipes on top of foil, this time with the new HVP and studs as the base. The studs prevent the HVP from touching the kimwipes.
The HVP assembly, from out of vacuum side in (with nipple), is the outer viewport (what holds vacuum and what we replaced today), the heater part, and the nipple.
Gaskets
- There is a normal 4.5" gasket between the outer viewport and the heater.
- There is a special laterally wide 4.5" gasket between the heater and the nipple.
- There is a normal 2.75" gasket between the nipple and SF port.
- All gaskets are silver coated, like all other GC gaskets, to be resistant to As (As degrades copper).

Vent Bravo
Remove the entire 4.5" to 2.75" nipple from the SF (2.75" flange), with the HVP assembly
- It is back heavy
- It has a rotatable flange
Foil over 2.75" flange of nipple and GC, using extra-small folded over pieces (~8x8" when unfolded)
- With the 2.75" nipple flange foiled, you can now put that down in the glovebag and hold the nipple to keep it upright

The viewport is held together with studs and nuts, that we will re-use for assembly.
Removed the studs holding the viewport assembly together
- You will need two wrenches
- Keep the bolts ~in the same position on one side
Remove the old outer viewport
- If it is good for re-use after etching, wrap it in kimwipes, then clean foil
- If it is leaking or not reusable, foil and trash it

Put down a clean foil workspace about 10x10" and put kimwipes down on it
Take the new outer viewport off the transfer case
Put the outer viewport out of vacuum side down onto clean kimwipes on clean foil
Put three studs through the new outer viewport bolt holes (carefully) so it can stand off of the kimwipes (and can be moved by holding a stud)
Put a normal gasket on the outer viewport
Put the heater on the outer viewport + gasket
Put a special gasket on the heater
Put the nipple on the heater
Finger tighten the three studs and nuts to keep the assembly together
Flip assembly over for easier insertion of studs
Insert stud, put nut on stud, and finger tighten; repeat for all studs
- In this method, I'd advise putting the stud through from underneath, holding the nut stationary on the stud tip, and rotating the stud til the nut is on the stud securely, then rotate the nut; this will minimize the chance you drop the nut on the viewport while trying to screw it onto the stud.
Wrench tighten nuts carefully while someone holds the nipple
We will check the tightness once the nipple is mounted on the SF
Our HVP assembly was then complete

See Notes below for hints
Use gasket clips to put a 2.75" silver gasket on the SF 2.75" port
P1 and P2 will need to work together to:
- get the nipple with HVP assembly onto the SF port
- remove the gasket clips and seat the nipple properly
- keep pressure on the nipple to stay seated
- insert ALL bolts to finger tight
- keep the nipple where it needs to be
- rotate the nipple into the proper position
- tighten down the bolts, keep the nipple level
- tighten down the bolts fully
- you can then release pressure on the nipple
P3 can help with gas and handing P1 and P2 tools-- P1 and P2 need to focus on keeping the nipple level and tightening it down
Once the nipple was fully tight, we checked the studs on the HVP assembly for tightness.
Pump down the chamber.
Leak check the HVP assembly, shutters, and things we were working near (e.g. cell power and thermocouple feedthroughs, N2 cell feedthroughs)

Working that far back on the SF (as opposed to nearer us such as cells) required lots of leaning into the bag. It also required extra care due to proximity of the shutters.
Taking the nipple off was annoying because it would want to tip down, but took just a few minutes.
The gasket clips for the 2.75" flange (on the SF, for the nipple) didn't even fit on right due to the shutter flanges-- luckily they worked really well.
Putting the nipple back on was very annoying because of the nipple trying to tilt down, and the glovebag making it hard to support it properly for bolt tightening. One person had to hold the nipple up.
In addition, the shutters made it hard to tighten more than 1/12 of a turn at a time-- this in turn would make it hard to tell if we were getting close to done with the tightening.
I tried using at least six different wrenches before we found one that worked well. It was a 1/4" 12 point head on a short two-axis bendable wrench extension/make-shift handle. It allowed me to put a 90 degree bend between the handle and wrench head, and the length of the two-axis part set the handle back so it didn't hit the shutters.
Don't know where to put this but the heated viewport is sapphire on the inside. The outside was sapphire in the 2019ish range, but a gasket leak in 2021 led us to go back to quartz per Veeco's recommendation. 2 years later and we are switching back to sapphire because of two different leaks in the quartz/metal seal.